Can masterbating too much make it tougher to ejaculate during sex or when receiving oral? Is it that my body is use to pressure of hand?

Porn addiction? Now that porn is so widely available, masturbation watching porn has resulted in porn addiction for some and increasing difficulty in getting aroused and erect when trying to engage in normal intercourse. For more information on this see
Probably. Now, having said probably, it depends on how soon after M that you try for oral or penetrating sex . We all have that recovery period after C. That varies as well with male/female and age. If you can, try to have at least 12 hours between climaxes. Try to have an intense foreplay as well. Again each person is different. You must find what works for you and your partner. .